Fix laravel version

Author: m-tanabe

caliper/composer.json

@@ -5,9 +5,9 @@
     "license": "MIT",
     "require": {
         "php": "^7.3",
-        "illuminate/database": "5.8.*",
+        "illuminate/database": "6.4.*",
         "imsglobal/caliper": "dev-develop",
-        "laravel-zero/framework": "5.8.*"
+        "laravel-zero/framework": "6.4.*"
     },
     "require-dev": {
         "fzaninotto/faker": "^1.8",